Before, unlocked iPhones on T-Mobile could only access the carrier's slower Edge (2G) network. But T-Mobile has flipped on a new spectrum in the northwest, Nevada, and northern California.

Although T-Mobile doesn't sell the iPhone, you can still buy an unlocked model directly from Apple at full price and insert your T-Mobile SIM card. T-Mobile will even give you the special micro SIM card that fits in the iPhone 4 and iPhone 4S if you ask.

Are you using an unlocked iPhone on T-Mobile? Have you noticed 3G working now? Let us know in the comments and tell us where you're getting the signal from.